1. Field of the Invention
This invention relates to a catalytic composition which can be employed for the conversion of petroleum products and in particular for isomerization, alkylation, dealkylation and polymerization of hydrocarbons; the invention further relates to a corresponding method of conversion.
2. Description of the Prior Art
It is known that in the field of petroleum refining, many conversion processes are carried out by means of catalysts and have an acid character. Acid catalysts which can be mentioned by way of example include aluminosilicate, the zeolites, aluminum chloride and bromide, the chlorinated aluminas and the liquid mineral acids such as sulphuric acid, hydrofluoric acid and phosphoric acid.
Recent researches have led investigators to develop superacid catalysts.
As disclosed in French patent No 2,005,043, the isomerization of aliphatic hydrocarbons containing at least 5 carbon atoms can be carried out by means of an acid catalyst constituted by a combination of hydrofluoric acid and antimony pentafluoride in the presence of hydrogen.
The isomerization of normal and naphthenic paraffins has been performed in accordance with the method described in U.S. Pat. No. 3,594,445 by employing a catalyst containing (1) a fluoride of a metal of Group V such as antimony pentafluoride and (2) a fluorosulphonic acid in the presence of hydrogen and of an olefin and/or of an alkylfluorosulphonate.
Another catalyst which is used for isomerization, alkylation and polymerization has been described in U.S. Pat. No. 3,678,120. This catalyst comprises antimony pentafluoride and hydrofluoric acid or a fluorosulphonic acid.
Finally, it is disclosed in U.S. Pat. No. 3,708,553 that the alkylation of hydrocarbons can be carried out by means of a catalyst consisting of a Lewis acid and a strong acid selected from fluorosulphonic acid and trifluoromethanesulphonic acid.